Pathological gambling is recurrent maladaptive gambling behavior that persists despite harmful negative consequences or a desire to stop. Although the amount of research focused on gambling has increased in recent years, only about 3% involves controlled experimentation. Most research that does exist with human participants suffers from serious methodological shortcomings, highlighting the need to develop more rigorous methods for studying the variables contributing to problem gambling. Animal research can alleviate many procedural limitations by allowing for controlled experimentation over extended periods of time. The primary goal of the proposed research is to develop a rigorous animal model of gambling that captures important features of human gambling, such as those related to increased preference for risky alternatives. A critical feature of gambling is the unpredictability of win amounts, yet little empirical work has examined such effects on continued risk taking. One current research aim is to conduct a controlled analysis of amount preferences using a token reward methodology, which allows for rewards to be delivered in varying magnitudes and later exchanged for food. By systematically altering the magnitudes for certain and uncertain payoffs, we aim to empirically establish the value of the two alternatives in relation to the proportion of tokens provided by that alternative. These manipulations will determine conditions that optimally produce preferences for the uncertain (risky) and certain (non-gambling) win amounts. Additionally, it has been demonstrated that organisms are more risk-prone when their income is restricted. A second aim is to examine how the amount of available income influences preference for the unpredictable reward amount. Token rewards permit a methodology analogous to currency in humans, in which the amount of available income can be manipulated. Subjects will be provided with income tokens, which can then be individually traded for gambling opportunities. Such manipulations address how different income levels affect preference for uncertain payoffs, in addition to evaluating preferences between different distributions of gambling outcomes. [unreadable] [unreadable] PUBLIC HEALTH RELEVANCE: The proposed research is relevant to public health in that the development of an animal model of gambling is necessary to empirically evaluate factors that may function to reduce preferences for risky, unpredictable outcomes. When variables contributing to risky choice are better understood, pharmacological and behavioral variables hypothesized to reduce such behavior can be explored in a controlled experimental environment free of limitations imposed by current gambling research. Beyond a model of gambling, this research has implications for understanding risky behavior in other characteristically impulsive populations. [unreadable] [unreadable] [unreadable]